Emily says (September 2011):
"With the addition of the following beer, Southern Tier is now not completely vegan across brews. Info from their website http://www.southerntierbrewing.com /beers.html
Crème Brûlée Imperial Milk Stout PLEASE NOTE: This is a Milk Stout. Lactose sugar is added and is present in the product. LOTS of vegan options, but this stout is generally on tap and no bottle warnings are available to staff."

Scott writes:
I called Southern Tier and spoke with the brewmaster, and was told that all of their beers are vegan. unfortunately I couldn't get e-mail confirmation because they don't have one listed.